My time playing with hardware RAID cards is over. My disks spent their time dropping on different builds (even with TLER disks only). For a home NAS, a synology style linux software RAID with regular data scrubbing is the peace of mind solution. For the cache problem, a cheap UPS that lasts the few minutes required to gracefully shut down is a good enough solution. As for performance, my bottleneck is the 1 gigabit port on my laptop anyway. And I don't see any improvement on the horizon for that anyway.